When to apply grub control
in New Hampshire
Enter your New Hampshire ZIP code. We'll tell you the best time to apply grub control based on real weather station data and Growing Degree Days.
Data details
What to buy for this result
Some links are sponsored. We may earn a commission, but your ZIP result determines which product type we show.
Preventive grub control
Chlorantraniliprole
Scotts GrubEx
Best fit: You want to stop this season's grub damage before it starts.
Helps you avoid paying for rescue treatment later when timing still favors prevention.
Must be applied before grubs are active; needs watering in
Curative grub treatment
Trichlorfon
Bayer Dylox 6.2
Best fit: Active grubs are already feeding and turf is lifting or thinning.
Helps you avoid buying a preventive product after the useful window has likely passed.
Only works on active grubs; short residual
How GDD Predicts Grub Activity
Growing Degree Days (GDD) track accumulated warmth in your soil since January 1. When the average daily temperature exceeds 50°F, the difference is added to your running total. Japanese beetles and other scarab beetles emerge to lay eggs when GDD reaches roughly 1,000–1,300. Preventive grub control products need to be in the soil before those eggs hatch — that’s the window this tracker identifies.
Grub Control GDD Thresholds
Why Grub Control Timing Matters
Preventive grub products like chlorantraniliprole (GrubEx) work by creating a treated zone in the soil that kills grubs as they hatch and begin feeding on roots. Apply too early and the product may degrade before peak egg-laying. Apply too late and grubs are already established — you’ll need a more expensive curative product. GDD tracking ties your application to actual soil temperature rather than calendar dates, which vary from year to year.
About New Hampshire Lawns
New Hampshire is in USDA Hardiness Zones 3b-6a. Common grass types include Kentucky Bluegrass, Fine Fescue, Perennial Ryegrass.
For more lawn care information specific to New Hampshire, visit the UNH Cooperative Extension.
Common New Hampshire grub control questions
When should I apply grub control in New Hampshire?
Use Growing Degree Days tracking for precise grub control timing in New Hampshire. Enter your ZIP code for a location-specific recommendation based on real weather data.